The University of Minnesota's Landscape Arboretum draws thousands of visitors to view acres of colorful plants and flowers, but an exhibition opening there this week focuses on a more mundane topic: the dirt that makes it all happen.

"Dirt-O-Rama" will have three display areas and special programming through mid-October to demonstrate how soil is filled with life, and how it needs to be cared for as much as the roses, dahlias, tomatoes and peppers that gardeners tend so scrupulously each year.

In many ways dirt is a "hidden frontier" that's taken for granted, said exhibit curator Sandy Tanck. "Almost anywhere you stand on the planet, there is actually more sheer tonnage of life and more different kinds of life living beneath your feet than you can see around you on the surface," she said.

People are naturally "surface-centric," she said, but farmers and gardeners know that soil is loaded with microbes and insects, and that its fertility needs to be preserved and nurtured.

The exhibit weaves these themes into a number of displays, demonstrations and children's activities.

An "Art of the Earth" outdoor sculpture display shows the work of five winning teams of artists. One is a giant walk-in anthill, and another displays huge worms surfacing from arboretum soil. Another includes a set of sonic flowers and the chance to listen to the earth's heartbeat.

Compost Corner shows how to turn yard and kitchen organic waste into rich, valuable compost. "Nearly one-third of what goes to landfills and incinerators is organics that could be composted and returned to the soil," Tanck said. Individuals and local governments are increasingly interested in rescuing that waste and turning it into "gardener's gold," she said.

"Dirt Lab" will let visitors compare sandy, silty and clay soils and find out how compost can improve each of them for gardening. It will focus on practical tips such as how to test whether soil is too compact or lacking in nutrients, and how to recognize and use different kinds of compost.

"Clayhouse" will bring two Arizona clay artists and adobe builders to the Arboretum for three weeks in July to work with children and create a child-friendly earthen structure. They will use local clay, wood and straw to build a circular shape with an exterior winding staircase.

On the scientific front, master gardeners will evaluate gardens treated with biochar, a carbon-rich byproduct of biofuels that will be added to soils.

Tanck said that the new children's Green Play Yard will offer its share of activities, with a mudpie kitchen and other hands-on projects each weekend.

Arboretum Director Ed Schneider said that the exhibition's goal is to appeal to all ages and sensibilities, with practical tips and education accompanied by whimsical art and playful structures. Dirt is a timely topic, he said, and there are growing demands nationally and globally to produce more food, animal feed, fiber, bioenergy and other crops.

Tanck acknowledged that dirt is not glamorous, but said that Arboretum visitors surveyed last year expressed interest in the topic. "It's an area where there are some relatively simple positive actions that anyone can take at home and make a difference," she said.

Tom Meersman • 612-673-7388